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Published on: April 18, 2019
Comparative evaluation of tigecycline susceptibility testing methods for expanded-spectrum cephalosporin- and
Olympia Zarkotou1, Spyros Pournaras, George Altouvas
1Department of Microbiology, Tzaneio General Hospital, Piraeus, Greece.
Abstract:
We evaluated the Vitek2, Etest, and MIC Test Strip (MTS) methods of tigecycline susceptibility testing with 241 expanded-spectrum cephalosporin-resistant and/or carbapenem-resistant Enterobacteriaceae and Acinetobacter baumannii clinical isolates by using dry-form broth microdilution (BMD) as the reference method. The MIC(50/90)s were as follows: BMD, 1/4 μg/ml; Vitek2, 4/≥8 μg/ml; Etest, 2/4 μg/ml; MTS, 0.5/2 μg/ml. Vitek2 produced 9.1/21.2% major errors, Etest produced 0.4/0.8% major errors, and MTS produced no major errors but 0.4/3.3% very major errors (FDA/EUCAST breakpoints). Vitek2 tigecycline results require confirmation by BMD or Etest for multidrug-resistant pathogens.
